This invention relates to substantially clear, abrasion resistant, impact resistant composite articles comprising a substrate of melt processable copolyester-carbonate copolymer wherein the molecules consist essentially of relatively short polyester segments composed of the bisphenol-A ("BPA") moiety and about 1 mole, especially 0.8 to 1.3 moles, per 2 moles of BPA of an aromatic dicarboxylic acid moiety, of which a major proportion is the terephthaloyl moiety. These ester segments are connected together in the copolymer by carbonate links and by relatively short, bisphenol-A polycarbonate segments. Such melt processable copolyester-carbonate copolymers wherein the dicarboxylic acid moiety is terephthaloyl, and preparation thereof, are described in copending U.S. patent application Ser. No. 764,623 of Prevorsek and Kesten, filed Feb. 1, 1977 now U.S. Pat. No. 4,156,069, patented May 22, 1979. Furthermore, such copolymers and preparation thereof are exemplified in Example III of the parent application of the above Ser. No. 764,623 (Ser. No. 672,945, filed Apr. 2, 1976 and now abandoned).
The subject polyester-carbonate copolymers are melt processable in the sense that upon molding for 10 minutes at 320.degree. C. to form a plaque, said polymerr changes in viscosity number by no more than 10% as measured in 40:60 weight ratio of tetrachloroethane:phenol at 25.degree. C. and 0.5 gm/dl concentration; and when heated under purified nitrogen for 30 minutes at 350.degree. C. then dissolved as a 2% (gm/ml) solution in dichloromethane, the polymer develops a "yellowness index" per ASTM test number D 1925 using a 2 cm path, of no more than 10.
The further component of the composite articles of this invention is a layer of polymerized allyl diglycol carbonate (hereinafter polymerized "ADGC") which is in direct adhesive contact with the polyester-carbonate copolymer substrate without substantial penetration of the copolymeric substrate by the polymerized ADGC.
It is known to produce hard, abrasion resistant surfaces on bodies of high impact resistant resins such as bisphenol-A polycarbonate resins. One proposed method is described in U.S. Pat. No. 3,763,290 of Oct. 2, 1973 to Sheld. A polyamide interlayer is formed upon the polycarbonate core and an ADGC monomer layer is applied over the interlayer and then is thermally polymerized; e.g. in a closed mold kept in an oven at 65.degree. C. for 12 hours using the conventional catalyst for ADGC polymerization, namely "IPP" (di-isopropyl peroxydicarbonate). The polyamide interlayer protects the polycarbonate core against attack by the ADGC monomer, which would occur and cause haziness bordering on opacity, in absence of such protective layer. See Example 7 of U.S. Pat. No. 3,763,290 above cited.
Another proposal for obtaining a polymerized layer of ADGC upon a body of bisphenol-A polycarbonate resin is the subject of Japanese Patent 74 97,037 (Chemical Abstracts, Vol. 82, 1975, 100295m). In accordance with this Japanese patent, the polycarbonate resin article is coated with a low molecular weight polymer or copolymer from ADGC monomer, which low molecular weight polymer is thereafter polymerized by UV radiation. The low molecular weight polymer itself is obtained by UV polymerization and is isolated as a white paste, which is heated to 80.degree. C. and coated onto the polycarbonate article.